Demand for electric power has grown significantly faster than the transmission system's capability to deliver it, and deliver it reliably. As a result, the overhead transmission and power distribution system is being operated in a manner for which it was not designed; bottlenecks and congestion, blackouts, equipment damage, and system disturbances are becoming widespread, and are occurring with ever increasing frequency.
Real-time monitoring of critical, congested transmission circuits would improve reliability, relieve congestion, increase available transmission capacity (“ATC”), and safely allow more power to be moved over existing circuits than is presently possible. As a result, the existing system would serve more demand; operating revenues could be increased, and some demand-driven new construction and upgrade costs could be deferred. At the same time, system operational safety, reliability, and power transfer capability can be improved.
Existing real time (“RT”) monitoring and dynamic thermal circuit rating (“DTCR”) systems have significantly expensive total installed costs. As a result of the cost and other product issues, the market penetration, acceptance, use, and growth of these technologies have been impeded. The sensor of this invention will be far less expensive than existing sensor and DTCR technologies, will be capable of easy and rapid installation and calibration, and will enable widespread, low-cost implementation of DTCR.
The improvements necessary to relieving bottlenecks and congestion in transmission lines, while simultaneously maintaining reliability, have been studied thoroughly, reported in detail, and recommended time and again. At best it is a $50-100 billion, decades-long effort. While the required improvements are mostly understood, and have been detailed and charted, they are off to a very slow start. While a fraction of these improvements (including appreciable new construction) began in the late 1990's, and are underway today, the improvement rate is still very significantly lagging demand growth.
Congestion costs electricity consumers approximately four billion dollars per year. Congestion-related costs could be significantly decreased if, while maintaining reliability, increased transfers across congested overhead transmission paths were allowed. Increased transmission capacity would improve grid reliability by allowing regions to share capacity reserves. Real time-monitoring of congested circuit parameters is a focal point for efforts directed towards higher grid efficiency and reliability via improved measurement and grid visualization. Parameters include conductor sag, temperature, current, ampacity, and ATC (“available transmission capacity”). When these parameters can be determined accurately, and in real-time, latent or “hidden” transmission capacity can be revealed; this can then be monitored, quantified, logged, and modeled. Ultimately, and more importantly, such transmission capacity can be capitalized on via dynamic thermal circuit rating and operation. Real time dynamic thermal circuit rating (“RT-DTCR”) systems maximize transmission circuit performance (ATC, ampacity, efficiency) while simultaneously maintaining reliability.
While a few commercial high voltage transmission line (“HVTL”) sensors and DTCR systems have become available over the years, acceptance, market penetration, use, and growth-in-use have been impeded by a number of factors. Technical issues (e.g., system failure, sensor impacts on reliability, poor accuracy, frequent loss of calibration, complex/lengthy/invasive installation or calibration) have plagued some technologies. More important has been the very high total installed cost. An overhead transmission line (OHTL) sensor/DTCR product with drastically lower costs would represent a dramatic improvement over existing commercial technologies.
Efforts to develop devices aimed at measuring conductor capacity, usage, and availability are hindered by complexity in design or installation. Genscape, Inc., for example, has filed multiple patent applications for their method of monitoring power and current flow in phase conductors. Several of the Genscape, Inc. publications (e.g., U.S. Pat. No. 6,714,000; U.S. Pat. No. 6,771,058; U.S. Pat. No. 6,956,364; and U.S. Patent Application No. 20050162148) require magnetic field measurements and electric field measurements to derive electrical power dynamics in the facility. Genscape's dual measurements entail significantly intricate data processing to estimate the power flow (MW) in high voltage transmission circuits.
Genscape's U.S. Patent Application 20070052493 utilizes magnetic flux measurements to determine which position below an overhead conductor is optimal for detecting changes in magnetic field. The '493 publication gives little detail regarding the manner by which the data gathered by the process therein could be used to determine additional useful parameters such as phase conductor magnitude, phase angle, cable heights, temperature, and ampacity.
U.S. Patent Application 20050286190 to Rostron discloses an electric power monitoring system using electromagnetic field sensors located remotely from the phase conductors. Rostron does not disclose the mathematical bases and algorithms for unknown system variables. At best, Rostron discloses the idea that measuring the electromagnetic field from a fixed, above-ground pedestal or platform can be used in predicting phase currents. Rostron offers little more detail.